A new approach to fused 1,2-diazepines by cyclization of enhydrazines with alpha- and beta-keto esters

• Published in: Heterocycles Vol. 47; no. 1; pp. 315 - 327
• Main Authors: Yamasaki, T, Nishida, K, Okamoto, Y, Okawara, T, Furukawa, M
• Format: Journal Article
• Language: English
• Published: OXFORD Elsevier 01.01.1998
• Subjects: Chemistry; Chemistry, Organic; Physical Sciences; Science & Technology; HETEROCYCLIZATION; PYRIMIDO<4,5-C>PYRIDAZINES; DIMETHYL ACETYLENEDICARBOXYLATE

The cyclization of 6-(1,2-diethoxycarbonylethylidene)hydrazino-1,3-dimethyluracil (3) and 6-(1,2-diethoxycarbonylethylidene)hydrazino-3-methyl-2-methylthiopyrimidin-4(3H)-one (8) in the presence of polyphosphoric acid (PPA) provided 2,5-dihydropyrimido[4,5-c]-1,2-diazepine-5,6,8(1H,7H,9H)-trione (4)...